弹性运动（二）：二维弹性运动

最新推荐文章于 2025-07-11 11:48:03 发布

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#Spring #Flash

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本文介绍了一个使用ActionScript 3.0实现的弹簧效果模拟程序。该程序通过计算与目标点的距离来调整物体的速度，并引入了重力和摩擦力的概念，使得物体能够表现出真实的弹簧运动效果。此外，还使用鼠标位置作为目标点，使效果更加直观。

package 
{
	import flash.display.Sprite;
	import flash.events.Event;

	/**
	 * ...
	 * @author zkl
	 */
	public class Spring1 extends Sprite 
	{
		private var ball:Ball;
		private var vx:Number = 0;
		private var vy:Number = 50;
		private var spring:Number = 0.1;
		private var friction:Number = 0.95;
		private var targetX:Number = stage.stageWidth / 2;
		private var targetY:Number = stage.stageHeight / 2;

		public function Spring1():void
		{
		    init();
		}
		private function init():void
		{
		    ball = new Ball;
			addChild(ball);
			//ball.y = stage.stageHeight / 2;
			addEventListener(Event.ENTER_FRAME, EnterFrame);
		}
		private function EnterFrame(e:Event):void
		{ 
			//与目标点的距离：
			var dx:Number = targetX - ball.x;
			var dy:Number = targetY - ball.y;
            //下面计算加速度。加速度与距离成正比，也就是距离乘以 spring 的值
			var ax:Number = dx * spring;
			var ay:Number = dy * spring;
            //把加速度加到速度向量中。
			vx += ax;
			vy += ay;
			//引入摩擦力
		    vx *= friction;
			vy *= friction;

			ball.x += vx;
			ball.y += vy;
		}
	}
}

最后加入重力，修改如下

package 
{
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.display.Graphics;
	/**
	 * ...引入y向速度后为二维弹性运动
	 * @author zkl
	 */
	public class Spring1 extends Sprite 
	{
		private var ball:Ball;
		private var vx:Number = 0;
		private var vy:Number = 20;
		private var spring:Number = 0.1;
		private var friction:Number = 0.95;
		//重力
		private var gravity:Number = 8;
		//private var targetX:Number = stage.stageWidth / 2;
		//private var targetY:Number = stage.stageHeight / 2;

		public function Spring1():void
		{
		    init();
		}
		private function init():void
		{
		    ball = new Ball;
			addChild(ball);
			//ball.y = stage.stageHeight / 2;
			addEventListener(Event.ENTER_FRAME, EnterFrame);
		}
		private function EnterFrame(e:Event):void
		{ 
			//与目标点的距离：
			var dx:Number = mouseX - ball.x;
			var dy:Number = mouseY - ball.y;
            //下面计算加速度。加速度与距离成正比，也就是距离乘以 spring 的值
			var ax:Number = dx * spring;
			var ay:Number = dy * spring;
            //把加速度加到速度向量中。
			vx += ax;
			vy += ay;
			vy += gravity;
			//引入摩擦力
		    vx *= friction;
			vy *= friction;

			ball.x += vx;
			ball.y += vy;

			drawLine(mouseX, mouseY, ball.x, ball.y);
		}
		private function drawLine(x1:Number,y1:Number,x2:Number,y2:Number):void
		{
		    graphics.clear();
			graphics.lineStyle(1);
			graphics.moveTo(x1, y1);
			graphics.lineTo(x2, y2);
		}
	}

}